Sound-Base Audio has released Retro Boy, a free chiptune synth VSTi for Windows.

Retro Boy is a virtual analog chiptune synthesizer/emulator. It does not specifically emulate a single device or sound chip, but it was made with a certain handheld gaming system in mind. The goal was to make a simple, minimal, synth that could create "8-bit music" without being overly complicated or requiring much knowledge from the end-user.

There is an XL version of Retro Boy in the works. However, there is no definite time as to when it will be made available. Check SBAudio's DevLog for any future updates on the development of the XL version.